Bis (trimethyllead) sulfide



United States Patent Ofiiice 3,973,852 Patented Jan. 15, 1963 3,073,852 (TRIMETHYLLEAD) SULFIDE San Rafael, Calif, assignor to California San Francisco, Calif, a corpo:

BIS Peter Ballinger,

Research Corporation, ration of Delaware No Drawing. Filed Sept. 30, 1960, Ser. No.

1 Claim. (Cl. 260-437) This invention relates to a novel organo-metal antiknock compound. More particularly, the invention is concerned, with a superior new lead sulfide antiknock compound for hydrocarbon fuels of the gasoline boiling a Gasoline compositions of high octane number are commonly required for modern spark ignition internal combustion automobile and'aircraft engines. Engines of these types in general use today are designed with high compression ratios for more efiicient operation. Since the present trend is toward engines of still higher compression ratios for lncreased power and improved performance, there is a constant demand for gasoline compositions of even higher octane number.

Improved methods of refining and blending gasoline base stocks, and additives such as lead tetraethyl, have been employed to meet the demands for higher octane number gasoline compositions. However, it has been generally realized that there is at present a limit to the improvement in octane number that can be obtained by such conventional methods and additives. New gasoline base stocks with the combination of dififerent additives are greatly needed, therefore, to avoid present limitations and provide gasoline compositions of high octane number for future use in automobile and aircraft engines.

It has now been found that a superior new gasoline composition of high octane number is provided by a hydrocarbon base fuel boiling in the gasoline boiling range, containing bis(trimethyllead) sulfide, a novel lead compound, in amounts sufiicient to improve the octane number, preferably, at least 0.5 milliliter per gallon of base fuel.

The improved gasoline compositions containing the new antiknock compound of the invention show unexpectedly high octane numbers. Hydrocarbon base fuels, together with bis(trimethyllead) sulfide and mixtures more, it has been widely recognized that sulfur is ordinarily antagonistic to lead The hydrocarbon base fuel of the composition, according to the invention is prepared by conventional refining and blending processes. It normally contains straightchain paraflins, branched-chain paraflins, olefins, aromatics and naphthenes. Since straight-chain parafiins have a tendency to adversely alfect octane Generally dean ASTM (D-86) distillation with an initial boiling point of about 100 F. and a final boiling point of about 425 F. Preferably, the unleaded base fuel has a research octane number of at least 85 as determined by the accepted CFR engine carbon content of the preferred fuel may be as much as percent by volume. For best over-all engine performance, fuels containing in the range of 20 to 60 percent by volume of parafiinic and naphthenic hydrocarbons are preferred for volatility and other desirable gasoline characteristics. The more preferred hydrocarbon base fuels are also those which contain from 20 to 60 percent by volume aromatic hydrocarbons and from 0 to 30 percent by volume of olefinic hydrocarbons. Most preferably, a gasoline having all-around desirable characteristics has a clear octane number of at least and percent by volume of parafiin and naphthene hydrocarbons, about 30 to 40 percent aromatic hydrocarbons and about 5 to 15 percent olefinic hydrocarbons.

The bis(trimethyllead) sulfide is illustrated by the general formula For practical purposes, not more than about 4 milliliters of lead compounds per gallon is ordinarily used in the compositions. If desired, other octane-improving additives may be employed in addition to bis(trimethyllead) sulfide. These include other lead compounds such as lead tetraethyl, carbonyl derivatives of iron and cyclopentadienyl derivatives of metals such as manganese or Other gasoline additives, such as scavengers like ethylene chloride or bromide, oxidation inhibitors, corrosion inhibitors, surface ignition suppressants like phosphorus compounds, detergents, and the like may be present.

The following examples illustrate the composition of bis(trimethyllead) sulfide in accordance with this invention. Unless otherwise specified the proportions are on a weight basis.

EXAMPLE I This example shows the lead) sulfide.

tions and tests thereon are given in the following eX- These tests show the improved effect of the combination of particular hydrocarbon base fuels with bis(trimethyllead) sulfide.

The following table is a summary of the pertinent data of the examples. The hydrocarbon base fuel conterms 51 percent by volume of the parafiins and naphthenes, 25 percent olefins, This fuel has a weight.

with lead tetraethyl. parison are based on the Motor Method D-357 containing an equal lead concentration. For the purpose J of practical comparison this is 3.17 grams of lead per gallon. Such amounts are equivalent to the 3 cc. of tetraethyl lead per gallon employed in many gasolines. The gasolines containing the trimethyl lead methyl sulfide have approximately 0.01 percent of lead-bound sulfur in addition to the sulfur already present.

Table Example N0. Lead Compound Research Motor Octane Octane None-base fuel 94.4 82.5 Tetraethyl Lead 99.2 87.7 Bis(trimethyllead) sulfide 99.0 87.0

The examples summarized in the above table show that the improved gasoline composition of the invention containing the novel bis(trimethyllead) sulfide of the invention is surprisingly comparable on the basis of octane number rating to gasoline compositions of the type preferred heretofore.

The organolead compounds of this invention are also useful wherever oil-soluble lead compounds are desired. For example, fine particle dispersions of lead may be obtained by thermal decomposition of the trialkyl lead sulfide dissolved in liquid hydrocarbon, such as isooctane. Such fine metal dispersions of lead are useful as catalysts for certain reactions. The fine lead particles may be converted to lead oxides which are useful as lubricating agents. The lead compound of the invention may also be used as a free radical initiator in polymerization reactions.

I claim:

Bis(trimethyllead) sulfide.

References Cited in the file of this patent UNITED STATES PATENTS 1,949,948 Alleman Mar. 6, 1934 2,936,224 Fontana May 10, 1960 2,938,776 Hamer May 31, 1960 2,955,124 Blitzer et al. Oct, 4, 1960 OTHER REFERENCES Chem. Reviews, vol. 54, No. 1, pp. 146, 260-437. 

